### Astrometry: Looking for Pascal/Delphi functions

Posted:

**06 Jun 2019, 17:04**Dear all,

Until now I used for the astrometry calculations the Pascal/Delphi programs described by Mountenbruck and Pfleger in https://www.amazon.de/Astronomie-mit-de ... 3540577017 The claimed accuracy of their functions and procedures of about 1 arcsec was sufficient for my purposes. I would now like improving this accuracy. This likely means replacing/improving the following calculations:

-> Precession matrix for equatorial coordinates from equinox T1 to T2 (PROCEDURE PMATEQU)

-> Nutation equation: Transformation from mean to apparent equatorial coordinates (PROCEDURE NUTEQU)

-> Aberration, velocity vector of earth in equatorial coordinates (PROCEDURE ABERRAT)

-> Functions for calculating positions of Sun, Moon and Planets.

QUESTIONS:

1) Has someone here improved their Pascal/Delphi functions or knows someone else who has done this?

2) An other solution could exist by using in the Pascal code these SOFA functions http://www.iausofa.org/2018_0130_F/sofa/sofa_ast_f.pdf added as DLLs. Do you know someone who uses such DLLs in his Pascal code who would be prepared to show how it was done?

3) In this context it would also be of interest to use the JPL ephemeries. Again, do you know someone who uses them with a Pascal-code?

Thanks and regards

Marcel

Until now I used for the astrometry calculations the Pascal/Delphi programs described by Mountenbruck and Pfleger in https://www.amazon.de/Astronomie-mit-de ... 3540577017 The claimed accuracy of their functions and procedures of about 1 arcsec was sufficient for my purposes. I would now like improving this accuracy. This likely means replacing/improving the following calculations:

-> Precession matrix for equatorial coordinates from equinox T1 to T2 (PROCEDURE PMATEQU)

-> Nutation equation: Transformation from mean to apparent equatorial coordinates (PROCEDURE NUTEQU)

-> Aberration, velocity vector of earth in equatorial coordinates (PROCEDURE ABERRAT)

-> Functions for calculating positions of Sun, Moon and Planets.

QUESTIONS:

1) Has someone here improved their Pascal/Delphi functions or knows someone else who has done this?

2) An other solution could exist by using in the Pascal code these SOFA functions http://www.iausofa.org/2018_0130_F/sofa/sofa_ast_f.pdf added as DLLs. Do you know someone who uses such DLLs in his Pascal code who would be prepared to show how it was done?

3) In this context it would also be of interest to use the JPL ephemeries. Again, do you know someone who uses them with a Pascal-code?

Thanks and regards

Marcel